The present invention relates to a method of manufacturing a fluorescent screen for colour picture cathode ray tubes in which at least two patterns of the fluorescent material layer which are adjacent to each other are applied photochemically to the glass front plate of the tube and a pattern of the filter layer which is substantially everlaid with the corresponding pattern of the fluorescent material is also applied photochemically at least between a pattern of the fuorescent material layer and the front plate.
With colour picture cathode ray tubes, it is already known to assign colour filter layer parts to the individual fluorescent material layer elements of the fluorescent screen (U.S. Pat. No. 3,726,678, U.S. Pat. No. 3,114,065, German Offenlegungsschrift No. 24 42 167). The patterned application of the fluorescent materials for these fluorescent screens is undertaken as is known by using photochemical methods whereby polyvinyl alcohol, sensitized with ammonium bichromate, is used chiefly as the light-sensitive binding agent. The patterned exposure usually takes place with UV light.
Furthermore it is known that the patterns for the fluorescent material can either be punctiform or in strips.
It is further known for the manufacture of fluorescent screens for colour picture cathode ray tubes to use a diazonium compound as a sensitizer for the polyvinyl alcohol (German Offenlegungsschrift No. 22 57 920 and German Offenlegungsschrift No. 23 10 617).
With methods of manufacturing fluorescent screens having filter layers as described, for example, in German Offenlegungsschrift No. 24 42 167, colour filter layers are applied in the same manner as individual fluorescent material layers and this means that exactly the same operating processes are necessary for each colour filter layer as are necessary to apply the fluorescent material layers in each case. It is particularly expensive to carry out the necessary insertion and removal of the shadow mask during exposure in order to produce the desired pattern.